This invention relates to dual-mode visible and infrared lighting. Specifically, this invention relates to a dual mode visible and infrared lighthead for use with aircraft landing lights and searchlights, and for use with other vehicles.
Aircraft generally have landing lights mounted thereon to provide illumination during taxi, take-off, and landing when visibility is reduced by darkness or adverse weather conditions. Landing lights may be mounted in a fixed position on the aircraft; alternatively, the landing lights may be pivotable by drive means to extend from the aircraft when needed, and retracted to reduce drag when not in use. Searchlights are pivotable by drive means similar to landing lights, but include an additional capability to rotate up to 360 degrees in a plane perpendicular to the extend-retract plane. Military and law enforcement helicopters commonly use searchlights to aim a beam of light in a desired direction to illuminate targets.
With the advent of infra-red based Night Vision Imaging Systems (xe2x80x9cNVISxe2x80x9d) for covert operations, there arose a need for landing lights and searchlights that were compatible with NVIS by producing infrared light for illuminating the selected landing and search areas while eliminating visible light. Early NVIS-compatible landing and search lights used infrared light filters installed over conventional visible lighting systems. A disadvantage of early NVIS-compatible lighting systems was that the flight crew could not switch from visible to NVIS modes during a mission, since the infrared filters were required to be installed and removed while the aircraft was on the ground. This disadvantage was overcome by prior dual mode lightheads containing both visible and infrared lighting elements, such as Snyder, et al. U.S. Pat. No. 5,695,272. Dual mode lightheads allow the flight crew to switch between visible and infrared lighting modes by simply applying electrical power to either the infrared or visible portions of the dual mode lighthead as desired.
While prior dual mode lightheads offer significant advantages over early manually-installed filters, they suffer from several disadvantages. First, replacement of failed lamps is a cumbersome and difficult process owing to the segmented lens and filter assembly, which must be removed then re-sealed each time a lamp is replaced. This repair frequently causes damage to the reflectors, reducing the optical efficiency of the lighthead. In addition, dual mode lightheads typically emit lower light intensity than dedicated infrared or visible lighting systems, since the surface area on the lighthead available for the lighting system is divided between the visible and infrared portions. Further, prior dual mode lightheads utilize visible light sources coupled with infrared filters to produce the infrared light, generating high temperatures within the lighthead that can limit the life of the light elements, lenses, and sealing materials. There is a need for a dual mode lighthead that is easier to maintain, provides higher intensity light output, and operates at a lower temperature to extend lighthead component life.
This invention is directed to a dual mode lighthead that is easier to re-lamp, provides improved light output, and generates less heat as compared to prior dual mode lightheads.
Specifically, the present invention is a modular design incorporating a housing, preferably a cast aluminum housing. The housing is designed to accommodate installation of the lighting elements from the rear of the lighthead. This prevents contamination of the reflector with dirt, oil, or fingerprints that can reduce the optical efficiency of the reflector. Installing the lighting elements from the rear also reduces maintenance time, since the front lens does not have to be removed and then re-sealed.
Replacement of prior front-mounted halogen lamps involves grasping the glass envelope of the lamp to install it into a socket. Because the presence of contaminating agents such as dirt, oil and fingerprints on the lamp""s glass envelope can reduce the life of the lamp, maintenance personnel must use cotton gloves or other protective materials when replacing lamps. The present invention utilizes a visible light source that includes a base that allows maintenance personnel to handle and install the lamp from the rear of the lighthead without touching or otherwise contaminating the glass envelope. Further, the lamp base allows the visible light source to be easily installed and removed without the need for tools.
The invention also utilizes high intensity infrared diodes in contrast to the filtered visible light sources used in prior lightheads. High intensity infrared diodes offer increased infrared light emission along with higher efficiency, reduced power consumption, longer life, and reduced heat generation. The high intensity infrared diodes also facilitate faster and simpler replacement due to their modular design.
The present invention comprises a dual mode lighthead, comprising: a housing comprising front, rear, top, and bottom sectors; an attachment point connected with one of said sectors of said housing to connect the dual mode lighthead with means for positioning the lighthead; means for reflecting light mounted inside said housing, said means positioned to reflect light from the front sector of said housing; at least one high intensity infrared diode, said diode being installed into said housing from the rear sector of said housing and positioned to emit infrared light out of the front sector of said housing; at least one visible light source, said visible light source being installed into said housing from the rear sector of said housing such that said visible light source projects through said reflectors and emits light from the front sector of said housing; and at least one lens affixed to the front sector of said housing through which one of emitted visible and infrared light passes.
These and other features will become better understood with reference to the following description, appended claims, and accompanying drawings.